Ground strap for suppressing stiction during MEMS fabrication
AssigneeSiTime Corporation
InventorCharles Grosjean
Life of this patent
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Abstract
To suppress stiction of a MEMS resonator during fabrication, conductive structures of the MEMS resonator are electrically coupled via a ground strap during the step of forming isolation trenches around their contact structures. After the isolation trenches have been formed, the ground strap is transformed into a non-conductive material to complete the electrical isolation of the conductive structures. An etch mask formed on top of the ground strap prevents etching of the ground strap during the formation of the trenches. Depending on the etching process, the ground strap may be formed as a bridge that suspends above the isolation trench or as a column that extends down to the bottom of the isolation trench.
Claims23
A fabrication process for a microelectromechanical system (MEMS) comprising:
- forming a microelectromechanical structure and conductive structures around the microelectromechanical structure, including a conductive layer above the microelectromechanical structure;
- forming contact structures for the microelectromechanical structure and the conductive structures;
- forming a trench through the conductive layer around each contact structure while maintaining a conductive path so that the contact structure is electrically coupled to other contact structures through the conductive path and the conductive layer;
- and
- transforming the conductive path for each contact structure to be non-conductive to cause the contact structures to be electrically isolated from each other.
A method for fabricating a MEMS device, comprising:
- forming first and second conductive structures and a conductive layer above the first and second conductive structures, wherein one of the conductive structures comprises a microelectromechanical structure;
- forming an etch mask above the conductive layer, the etch mask partially exposing an area above an isolation trench that is to be formed through the conductive layer around a contact structure for one of the first and second conductive structures;
- etching the isolation trench through the conductive layer using said etch mask, wherein a conductive path from the contact structure to the conductive layer remains after etching;
- and
- removing the conductive path.
A method of manufacturing a device having an electromechanical structure and an electrode structure, comprising:
- forming an insulating layer on top of the electromechanical structure and the electrode structure;
- forming a conductive layer on top of the insulating layer;
- etching through the conductive layer using the insulating layer as the etch stop layer to partially form an isolation trench of a contact structure for one of the electromechanical structure and the electrode structure;
- and
- transforming one or more portions of the conductive layer that have not been etched to be non-conductive to complete the formation of the isolation trench.
Dependencies are inferred from the claim text.